Whatever happened to neighbors?

Humorist -- very fine humorist -- Fran Leibowitz recounted one time how when she was in junior high, she would get off the school bus, and would, at the age of 14 or so, light up a cigarette immediately after alighting, and then embark on her half mile walk home through her neighborhood.
"By the time I got home, my mother already knew I'd been smoking," she said. Her mother knew because at the very least, three neighbors would have called her mother and informed her of young Fran's transgression.
The anecdote came to mind in a conversation over coffee yesterday morning with a man who is, in fact, a neighbor, but whom I know via other means. In any case, we were wondering how the world become some a weird, obsessive-compulsive and paranoid place, that nobody knows their neighbors. Indeed, neighborhoods in the old sense no longer exist. There are areas with houses and shops, but they are not truly neighborhoods as the idea was once understood.
For example, and back to my friend, Fran. While her mother would have chewed her out for her smoking, her mother would also have been grateful they'd blown he whistle on her daughter. Indeed, if Fran's mother hadn't been home, the neighbor would have chastised the child on her own, without parental permission. And the parents again would have been grateful. Neighbors were part of the network of both discipline and care.
I live near a park. A quite pleasant park and recreation area. And the park gets vandalized. It gets vandalized, not by outsiders, but by kids from the neighborhood. Not horrifyingly vandalized, but you know, the usual shit. graffiti spray painted on surfaces -- graffiti of the most vile and angry invective. Littering abounds, the remnants of illicit drinking sessions, bottles, cans and so forth can regularly be found. I haven't run across remnants of juvenile alfresco sexual activity, and I'd rather not, thank you. But, I'm sure those too can be found if one looks.
Why the graffiti? Why the vandalism? Why the contempt for a provided neighborhood recreational spot?
Alienation (aside from less-than-room-temperature-IQs) is the word that comes to mind. In other words, the brats who do this stuff have no sense of ownership, no sense of belonging, so they act out by defiling. That to me is the reason (by the way, a reason is never an excuse) for much misbehavior in our communities. Nobody owns our communities any more, other than weasels at banks and government offices, so people don't have pride, and they don't have trust, and they don't have neighbors who they want to let into their lives. What if those neighbors are perverts who are going to molest the kids? What if that up-scale dwelling is really a meth lab or marijuana grow? No, no, pull up the drawbridge and make no interchanges with these people.
When I was a kid, and even when I was an adult, neighbors used to get together for block parties, barbecues, or even meetings about an issue of common concern. No more. Can you even name your neighbors more than one house or apartment away? I bet not.
Biblically we are told to love our neighbor as ourselves, and we are told to not covet our neighbors wife, no matter how hot she is. But, even in that, the biblical assumption is that you know these folk well enough to actually covet said hot and desperate housewife.
I'm not saying I can suggest an answer to this, but I think it's said that an important dynamic; indeed an important freedom has been supplanted by fear, mistrust and isolation. What a silly society we live in.